Electrosurgery is widely used for treating tissue abnormalities. One known electro-surgical device includes a probe having a first or “active” electrode extending from one end. The electro-surgical probe is electrically coupled to an electro-surgical generator, which provides electric current to the treatment site.
When configured as a monopolar device, a second or “return” electrode, having a much larger surface area than the active electrode, is positioned in contact with the skin of the patient. The surgeon may bring the active electrode in close proximity to the tissue, activate a switch, and cause electrical current to arc from the distal portion of the active electrode and flow through tissue to the larger return electrode. When configured as a bipolar device, no return electrode is used. Instead, a second electrode is closely positioned adjacent to the first electrode, with both electrodes being attached to an electro-surgical probe. As with monopolar devices, the electro-surgical probe is electrically coupled to an electro-surgical generator. When the generator is activated, electrical current arcs from the end of the first electrode to the end of the second electrode and flows through the intervening tissue.
Whether arranged in a monopolar or bipolar fashion, the active electrode may be operated to perform a particular function, i.e., to either cut tissue or coagulate tissue. When used to cut tissue, the electrical arcing and corresponding current flow results in a highly intense, localized heating, which breaks intercellular bonds and severs tissue. When used to coagulate tissue, the electrical arcing results in a low level current that denatures cells to a sufficient depth without breaking intercellular bonds. In other words, the low level current does not cut the tissue.
There are many medical procedures in which tissue is cut or carved away for diagnostic or therapeutic reasons. For example, during hepatic transection, one or more lobes of a liver containing abnormal tissue, such as malignant tissue or fibrous tissue caused by cirrhosis, are cut away. Various modalities, including mechanical, ultrasonic, and electrical (e.g., radio frequency or “RF” energy), can be used to resect tissue. Whichever modality is used, extensive bleeding can occur and may obstruct the surgeon's view and lead to dangerous blood loss levels, requiring transfusion of blood. These complications may increase the complexity, time, and expense of the resection procedure.
To prevent extensive bleeding, hemostatic mechanisms, such as blood inflow occlusion, coagulants, and energy coagulation (e.g., electro-surgical coagulation or argon-beam coagulation), can be used. When an electro-surgical coagulation device is used, the bleeding can be treated or avoided by coagulating the tissue in the treatment areas with an electro-coagulator that applies a low level current to denature cells to a sufficient depth without breaking intercellular bonds, i.e., without cutting the tissue. During a typical electro-surgical resection procedure, electrical energy can be conveyed from an electrode along a resection line in the tissue. The electrode may be operated in a manner that incises the tissue along the resection line, or coagulates the tissue along the resection line, which can then be subsequently dissected. In the case where an organ is resected, application of RF energy divides the parenchyma, thereby skeletalizing the organ, i.e., leaving vascular tissue that is typically more difficult to cut or dissect relative to the parenchyma.
When a blood vessel is encountered, RF energy can be applied to shrink the collagen in the blood vessel, thereby closing the blood lumen and achieving hemostasis. The blood vessel can then be mechanically transected using a separate instrument, such as a scalpel or scissors, without fear of blood loss. In general, for smaller blood vessels less than 3 mm in diameter, hemostasis may be achieved within 10 seconds, whereas for larger blood vessels up to 5 mm in diameter, the time required for hemostasis increases to 15-20 seconds. During or after resection of the tissue, RF energy can be applied to any “bleeders” (i.e., vessels from which blood flows or oozes) to provide complete hemostasis for the resected organ.
While known devices and methods have been used effectively in the past, they can be improved. For example, it would be desirable to be able to perform coagulation and cutting functions with the same instrument, thereby eliminating the need for separate instruments and disposing of the need for separate electrode and mechanical cutting devices. A single electro-surgical device that can perform both coagulation and cutting functions during resection procedures would eliminate the need to switch between different surgical devices during surgery and reduce surgery times. Further, it would be desirable to perform electro-surgical resections without charring tissue. When electro-surgically resecting tissue, care must be taken to prevent the heat generated by the electrode from charring the tissue, which generates an undesirable odor, results in tissue becoming stuck on the electro-surgical probe, and increases tissue resistance, thereby reducing the efficiency of the procedure.